Lenticular printing is used to provide an illusion of depth or animation to a two-dimensional printed image. Many existing lenticular printed media include an interleaved printed image with an array of lenticles placed over the interleaved printed image. The interleaved printed image is formed from a series of thin sections of two or more printed images that are formed in an alternating pattern on a print medium such as a sheet of paper. The lenticles are formed from an optically transparent material, such as a sheet of plastic, with a repeating lens-like structure that is aligned with the interleaved printed image. The lenticles focus light that reaches the interleaved image so that a viewer sees only a portion of the interleaved image when viewing the lenticular print medium from different viewing angles. In a simplified example, an interleaved image comprises alternating strips of blue and red ink that are aligned with a series of lenticles. The lenticles direct light rays from a first angle to the blue strips so that the image appears to be blue when viewed from the first angle. The lenticles direct light rays from a second angle to the red strips so that the image appears to be red when viewed from the second angle. As is known in the art, a lenticular printed medium provides an illusion of three-dimensional depth, transformation, or animation to multiple interleaved images as the viewing angle of the printed medium changes.
In many embodiments, the lenticles in a lenticular printed medium are formed from an optically transparent plastic sheet. The lenticles are formed using, for example, an ablation, molding, or an extrusion process that produces a series of lenticles in the plastic sheet. The plastic sheet is then aligned with the interleaved printed image to form the lenticular printed medium. Conventional lenticular printed images require comparatively thick plastic sheets that are formed with comparatively wide lenticles due to the physical tolerances of the plastic sheets that form the lenticles. Narrower lenticles enable printing interleaved images with narrower interleaved strips for lenticular images with higher resolution and visual fidelity.
More recently, techniques for generating a lenticular printed medium using inkjet printing have enabled the production of lenticular printed images using thinner print media with narrower lenticles that enable the production of higher resolution printed images. In one configuration, an inkjet printer ejects drops of an optically transparent ink onto the surface of thin transparent plastic sheet to form lenticles on one surface of the plastic sheet. The interleaved image is placed on the opposite side of the plastic sheet in alignment with the printed lenticles to form the lenticulated print. The use of a transparent ink to form the lenticles enables the production of substantially narrower lenticles than are practical with conventional plastic sheets, and the printed lenticles can be formed on transparent plastic sheets having thicknesses that are similar to ordinary printed paper instead of the much thicker plastic sheets used for conventional lenticulated print media.
One challenge that confronts lenticulated print media that are formed with inkjet printers is the potential for gaps or overlap between the printed lenticles that alter the focus of light that reaches the interleaved image. For example, FIG. 4A depicts prior art lenticles, such as lenticles 404A and 404B, that are formed with a gap between adjacent lenticles. The lenticles 404A and 404B are configured to focus light from different angles onto either of the interleaved images 408 or 412. In FIG. 4A, the lenticles 404A and 404B focus the illustrated light rays onto the interleaved image 408. In FIG. 4A, however, a gap formed between the lenticles 404A and 404B permits a portion of the light, such as the light ray 416, to be reflected from the interleaved image 412 instead of the interleaved image 408. FIG. 4B depicts another configuration where lenticles, such as lenticles 424A and 424B overlap each other. In FIG. 4B, the overlap between the lenticles diverts the focus for a portion of the light rays from the first interleaved image 408 to the second interleaved image 412. For example, the light ray 426 intersects an overlapping region between the lenticles 424A and 424B, and the overlapped transparent ink removes the focusing effect of either lenticle to enable the light ray 426 to reach the interleaved image 412 instead of the interleaved image 408. Consequently, systems and processes for forming lenticulated print media with lenticles that focus light with improved precision would be beneficial.